fix: install poetry-dynamic-versioning, update README

* README needs additional instructions since poetry's an extra now

.github/workflows/publish.yaml

@@ -21,6 +21,7 @@ jobs:
         run: |
           pip install pipx
           pipx install poetry
+          poetry self add poetry-dynamic-versioning[plugin]
           echo "$HOME/.local/bin" >> $GITHUB_PATH
       - name: Build
         run: |

README.md

@@ -17,7 +17,7 @@ automatically redirected to the proxy as well.
 Start by installing Poetry with pipx:
 
     pipx install poetry
-    pipx runpip poetry install poetry-plugin-pypi-proxy
+    poetry self add poetry-plugin-pypi-proxy[plugin]
 
 If you have already installed poetry, you only need to run the second command.